Module 11 12 Notes PDF

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Notes covering Lectures 11-12 from BSCI 1105, which is taught by Professor Denise Due-Goodwin....

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Module 11 Anthropocene Interactive Anthropocene: new geologic epoch marked by extensive human impacts on the environment - Begins either at start of industrialization (1750) or start of globalization (1950) → up for debate - Characterized by changes in landscape, ocean and atmospheric chemistry, species extinctions and invasions - Atmosphere: increased carbon dioxide, nitrous oxide and methane in atmosphere - Biodiversity: ~900 species have gone extinct in past 500 years; pace of extinctions greatly accelerated in past few decades, trending toward mass extinction - Cities: ~7 billion ppl inhabit planet; demands for land, water, food, energy reshaping the planet - Coastal habitats: vulnerable to pollution → agricultural runoff carries nitrogen and phosphorous into coastal waters, feeding plankton blooms that suffocate fish - Farms: converted natural ecosystems into farmlands release carbon into atmosphere, loss of biodiversity - Forests: deforestation reduces biodiversity, fragments habitats, impedes ability of species to adapt to global warming - Invasive species: consequence of extensive global trade/travel - Mining: causes erosion, pollutes waterways, disrupts geochemical cycles of metallic elements, carbon, nitrogen, and phosphorus - Ocean: overfishing depletes fish populations, can harm marine ecosystems - Water use: dams change seasonal runoff patterns and downstream ecosystems

Biodiversity Video

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Recognize that understanding complex interactions among species and their environment are a key goal of population, community, and ecosystem ecology

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Understand that scientific investigations in the realm of ecology can contribute to better decisions regarding conservation of biodiversity, sustainability, and informing environmental issues (note: ecology and environmentalism are not synonymous!)

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Biodiversity is viewed at various levels: genetic, species, and ecosystem

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Be able to describe the "dilution effect" as an example of why biodiversity matters ○ Dilution effect: term used to describe the impact of high diversity on reducing the risk of human exposure to lyme disease → greater the

Be able to describe the "portfolio effect" as a possible mechanism for ecosystem stability ○ Portfolio effect: phrase used to describe why it is that more diverse systems are more stable → related to economics ■ The more species included in an ecosystem, the more relatively stable that ecosystem will be because of the average of all the species

number of non-mouse hosts for ticks that exist in any given environment, the greater the ability to dilute the impact of whitefooted mice, which are the main reservoir for lyme bacteria ■ Lyme disease in humans likely emerged from the chain of events following habitat destruction ■ Bigger the forest the better in terms of protecting human health/risk of exposure to lyme ■ Diverse population of animals means ticks have multiple sources of blood meals, diluting impact of infection ● When habitat is damaged, some species disappear and mice proliferate, infecting ticks with lime and making them more dangerous to people

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Recognize the difficulties of estimating current extinction rates and making decisions about conserving biodiversity ○ We don’t know what the current extinction rate is because we do not know how many species we have on earth ○ Very difficult to determine which species play key roles in particular ecosystems, makes it hard to prioritize conserving certain species over others

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Consider the importance of genetic diversity in conservation ○ Important to understand relationships between species → which species have unique genomes over others

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Be able to define and explain the importance of sustainability ○ Sustainability: most reasonable means for reconciling two opposing forces: basic needs of humans and long term viability of environment we inhabit and rely upon ○ We are not currently living sustainably Mass extinction: dramatic spike in percentage of families of organisms vanishing from fossil record within relatively short periods of time - 6th mass extinction? → present rate of extinction exceeds anything found in fossil record over last 65 million years - Human behavior as the cause of extinction

Ch. 24/25 Biosphere: portion of Earth that contains living organisms, from atmosphere to depths of oceans Ecosystems: specific areas of biosphere were organisms interact among themselves and w physical/chemical env’t - Interactions w/in an ecosystem maintain balance in that area, which maintains balance of biosphere - Human activities can alter interactions between organisms and env’ts to reduce biodiversity Abiotic: non-living → soil type, water, weather Biotic: living → autotrophs or heterotrophs - Autotrophs: require inorganic nutrients and outside source of energy to produce organic nutrients for their own use (photosynthesis) → producers of

food Heterotrophs: need source of organic nutrients → consumers of food - Several levels of consumers in an ecosystem → food chain - Detritus feeders: heterotrophs that feed on detritus, decomposing particles of organic matter → earthworms, beetles, termites, ants, mushrooms, bacteria Niche: role of organism in an ecosystem → how an organism gets its food and interacts w other populations and its habitat WATER CYCLE Fresh water: renewable resources bc new supply always being produced - Possible to run out if available supply runs off instead of entering fresh water bodies/aquifers; can also become polluted - Increasing water supply is difficult → water conservation is essential CARBON CYCLE Carbon cycle: living and dead organisms contain organic carbon, serve as reservoir for carbon cycle - Decomposition of plants and animals returns carbon to atmosphere - Plant and animal remains transformed into fossil fuels over past 300 million years → coal, oil, natural gas - Inorganic carbonate accumulates in limestone and calcium carbonate shells - Transfer rates of CO2 between storage of carbon during photosynthesis and release during cellular respiration/decomposition is about = Human activities - Releasing large amounts of carbon into atmosphere → along with other GHGs, contributing to global warming NITROGEN CYCLE - Human activities alter transfer rates in nitrogen cycle by producing fertilizers from N2 - Fertilizer runs off into lakes/rivers → contributes to overgrowth of algae - Eutrophication: algal bloom → when algae die, decomposers use up all the oxygen in the water, resulting in massive fish kill - Similar process occurs w phosphorus - Acid deposition: occurs when nitrogen oxides and sulfur dioxide enter atmosphere from burning fossil fuels → gases combine w water vapor to form acids that return as acid rain - Smog: forms when nitrogen oxides and hydrocarbons (HC) from burning fossil fuels react in presence of sunlight PHOSPHORUS CYCLE - Human activities responsible for increasing phosphates in env’t - Mining, fertilizers, detergent use → excess levels of phosphates HUMAN POPULATION GROWTH - Population undergoing exponential growth → 83 million people added annually to world population - exponential growth indicates population is enjoying biotic potential → maximum growth rate under ideal conditions -

Growth declines bc of limiting factors → food and space Carrying capacity: maximum population the env’t can support for an extended period → hasn’t been determined for humans - MDCs: more developed countries; population growth is modest - LDCs: less developed countries; population growth is dramatic - Many countries in transitional stage between LDC to MDC Age structure - Pre-reproductive - Reproductive - Post-reproductive Ecological footprint: total amount of resources used by an individual to meet their needs Food - Enough food to supply 2,700 calories/person/day to support 7.6 billion people - Food comes from crops, animals, fishing - Soil loss: land suitable for farming/grazing animals being degraded → topsoil (richest soil) is being lost by water and wind - Green revolution: dramatic increase in yield due to introduction of new breeds of tropical wheat and rice in LDCs → helped world food supply keep pace w rapid increase in population - Most green revolution plants need high levels of fertilizer, water, pesticides to produce high yield - Genetic engineering: can produce transgenic plants w new/different traits → could result in another green revolution BIODIVERSITY Biodiversity: variety of life on Earth, described in terms of number of different species - Presently in biodiversity crisis bc of climate change and human population growth Loss of biodiversity: - Habitat loss - Alien species - Pollution - Overexploitation: occurs when number of individuals taken from wild population is so great that population can’t replace itself; becomes severely reduced → positive feedback cycle: smaller the population, more valuable its members and greater incentive to exploit remaining individuals - Ex: overfishing - Emerging diseases Value of biodiversity: - Medicinal value - Agricultural value - Consumptive use value - Indirect values: - Waste disposal: decomposers break down dead organic matter and other wastes to inorganic nutrients, which are then used by producers within ecosystems - Provision of fresh water -

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Prevention of soil erosion: intact ecosystems naturally retain soil and prevent soil erosion - Regulation of climate: forests stabilize climate bc they take up CO2 SUSTAINABLE SOCIETY Sustainable: society is sustainable when it is always able to provide same amount of goods and services for future generations as it does for current one, while preserving biodiversity - Incompatible w current level of consumption/waste Characteristics of a sustainable society: - Using renewable energy sources - Recycling materials - Efficiency and conservation - Preservation in rural areas → both terrestrial and aquatic ecosystems - Urban sustainability → serving needs of new urban arrivals without increasing urban spread

Module 12 Synchronous Lecture - 12/3/20 What is biodiversity? - Genetic diversity - Species diversity - Encountered more in media → may be less important than role different species play in maintaining ecosystems (ecosystem diversity) - Ecosystem diversity - As or more important than species diversity - Multiple species can play the same role in helping an ecosystem function → fill a particular niche Importance of diversity - Well-balanced ecosystem supports wide variety of species, each w different niche - If area suffers no major shocks (fire), succession eventually leads to stable mature community that changes very little over time - Mature communities = most efficient in terms of energy & nutrient utilization and most varied in terms of numbers of species - Mature communities can take hundreds of years to develop; may retain character for hundreds to thousands of years - When mature communities are disturbed, they don’t recover easily Healthy ecosystems: essential to maintain renewable/non-renewable resources - Productive → food & resources - Primary productivity - Biomass → more biomass = more resources - Most productive ecosystems sustaining most damage from human activity - Ex: coral reefs, Amazon rainforest - Stability - Resistant

- Withstand disturbance - Resist damage - Resilient - Bounce back after disturbance - Diversity-stability hypothesis - Portfolio effect: ecology is like the economy → the more different species you have, the more stable it will be - Diverse ecosystem is more productive and more stable → “healthier” Goods (renewable resources) - These are resources, that if managed in a sustainable way, can continue to support the population for the long term - Fisheries - Logging - Crops → medicinal/pharmaceutical value Ecosystem services (non-renewable) - Free → compliments of nature - Bee pollination - Nutrient cycling → keeping air & water clean - Human health a protection from diseases The “dilution effect” - Lyme disease - Infection risk strongly correlates to small mammal diversity - West nile virus - Infection risk strongly correlates to bird diversity - New world hantaviruses - Infection risk strongly correlates to rodent diversity - Dilution effect (facilitated by diversity) - Reduces encounters of vectors w more competent hosts - Suppresses populations of more competent hosts through ecological interactions - More effective w vector-borne transmissions (?) Human threats to biodiversity - Habitat destruction and fragmentation - Overexploitation (overharvesting, overfishing) - Invasive species - Climate change - Pollution Human population growth → more resources, greater impacts - We need to better understand not just human pop growth, but dynamics of other pops too, if we hope to preserve Human population growth - Has grown exponentially w industrial, medical, and technological advancements - Exponential growth cannot be maintained forever - Human population continues to grow, but more slowly - Dependent on birth rates and death rates

- When births > deaths → growth Concepts of population growth (or decline) - Exponential growth: pop grows at constant rate indefinitely - Logistic growth: pop growth is limited by env’tl factors such as available food sources, disease, and access to natural resources - Carrying capacity: maximum number of individuals in a pop that a particular area can support given available resources - Populations will fluctuate around carrying capacity as they briefly exceed it and then encounter disease or food shortage - Population growth limited by two factors - Density-dependent - Competition for resources - Build-up of poisonous wastes - Disease - Density-independent - Climate and weather - Disruption of physical env’t - Human influence Population dynamics - Size of populations doesn’t always remain stable - Some populations fluctuate in size - Other pops experience regular cyclic changes...